Circuit breaking apparatus



4 NGV, 24, 1931. MURRAY 1,833,173

CIRCUIT BREAKING APPARATUS Filed July 10. 1928 7 Sheets-Sheet 2 A TTORNEY yM Q Nov. 24, 1931. T. E. MURRAY I 1,333,173

CIRCUIT BREAKING APPARATUS Filed July 10. 1928 '7 Sheets-Sheet 4 //V VLA/ 4 TTORNEY mmmmwwmwmmmw Nov. 24, 1931. T. E'. MURRAY CIRCUIT: BREAKING APPARATUS Filed July 10. 1928 7 Sheets-Sheet 6 INVENTOR I j TTORAQIEY Nov. 24, 1931. T. E. MURRAY CIRCUIT BREAKING APPARATUS Filed July 10. 1928 7 Sheets-Sheet 7 12v VENTOR ZZ'OMAJZTJZ QR/PAK ATTORNEY Patented Nov. 24, 1931 Timon-s3. news, or pn mmynw Yong Joanna BRADLEY noun, THOMAS 1 mm? mm, .13. woman .numu,mcumons or THOMAS E. MURRAY,

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ma simple and inexpensive circuit lirezi'ker "xiiliiehcliiilie il se'dlin place' of the oil switch "'zuitl accessories now g 'alty u ed pnhi 'tEIlSIOiTCIICiUt'S. 1 V The l y g mwings illustrate emmunilmus 1912's. ism-1:1 1%. 291,686

overload, reverse current, reverse energy or other term of re'lay,or in fact-by :my usual r suitable automatic mechanism. It is de- Ybbiiiinehts of the invention. V circuit breaker which blows directly u n Fig; 15 p tii' g aftl'y' in section,=of the occurrence of a' dead short circuit.- hus *ofswitchesantl"fuses; r 1 the-circuit is bro'kenin much less "time than Figl is aidiagi-an ot' thesnne; 1i with previous devices whereithas been nec- :rnothe modification;

ii'xiil' "open 'pos'itignis irespectitei'ly (if A "the {4 is a sectional iew on the line' swi -13;

Fig. :5 is a vertical section through-one of histrat-ing another inotlification;

Figs. 2 ncl 3 are sectional views inxilesed switches;

" 9 f :inil 10' 'illhstrfiting another modifieition "Figs; '11 and h! simila Yiews -dfsti1l a perspective view in sectioniltmg the invention util zing :1 differpeoffuse;

undjahorizonttil section (if thef fuse andr ea suitable operating mechanism.

oil switch or circu it ilil'eal The instelL- tion dsignedfto nefil-ecethef :ei' which is com- 'mon'ly used onhigh-tenslon cif cnits. YIt may springs and other iievices device or to open the circuit mechanically through the operation eff-relays, trip coils, which must -'be set in motion.

conductors 10' mid-'11 lead to opposite connectors '12Fm0unte'don on inEm'leLt-ing base 13 forming the hottom df'a casing having side walls 14,. rear and front'walls 15, a longitu- I mnqmsmi, ASSIGNOBSTO fmn'rzzoroti 'rm nnwcn CORPORATION, AflOB-PQBQATION s s 1& signed to open the circuit by means of a. fuse essary to overcome the inertla oi mechanical -00 Referring first to Figs. 1 and I ,t he 1m n linal partition or barrier 15 and a t0p0r"' coverhereinaiftenreferredto. "There are-thus two separate "compartments carrying respectively the main and *the auxiliary switches hereiniifter described. Each connector caia fies two bi'furcat'ecl switch Blades 16 and '17."

Between the two connectors is a fixed vertical transverse liiart'ier 18 with 1 slot extending through it for the passage of verticallyslid- V At eachtsideof thecar-rier IQthere is a shelf -23 on which is s conducting plate '24 in contactwit'h :the upper end of the switch lilafle 2 1 and carrying three contactors 25 the lower ends of conductors '26jwhic'h lead to fuses 27, which jpass through {the "barrier foi'nietl by the u ppi' 'part of the carrier 19 of insiilaiting material;

lug-carriers "19 and 20 which operate the, movable switch hlades 21 ancl 22.

which are detach'zihly engaged by 'bl'ades on" The-car'lier 20 "is similar to but inoves' in dependently of the carrier 19. "It ,has at oacli'side'iishelf 28 with a cont-actor 29 connected.tofthe'switchlilade 22 and adapted of a conductor 30, the conductors 30 at opposite sides of the barrier being connected through a fuse 31 passing through the upper part of the insulating carrier 20.

The carrier 19 supports and operates, therefore, a double break switch 21 at each side, and between these switches there are three branches with a fuse in each.

The branches 26 may be in parallel as shown in Fig. 1; or they may be in series. The invention is useful with one or any number of such fuses. Since they are intended to take care of currents greatly exceeding normal, such as dead short circuits, and must therefore be of large capacity, it will generally be better to use severalfuses.

The carrier 20 supports a double break switch 22 in parallel with the switch 21; and in the connection 30 between the switch blades 22 there is a single fuse (though here again a plurality of fuses can be used). This fuse 31 is of considerably smaller capacit in amperes than the fuses 27. Instead 0 having a number of fuses 27 in parallel, each of such fuses may be made of larger capacity and the number of fuses correspondingly reduced.

In the mechanical operation of the breaker the carrier 19 is actuated before the carrier 20. Various ways of securing this timing may be utilized, Fig. 1 showing a manual operation. The lever 32 has a forked end with one prong 33 engaging a short slot 34 in the carrier 19 and with another prong 35 engaging a longer slot 36 in the carrier 20. When the lever arm 32 is raised the carrier 19 will be lifted, and with it the switch blades 21 so as to break the circuit through them, before llfting the carrier 20 and its switch blades 22.

I have provided also movable insulating barriers 37 and 38, Fig. 4, one pair on each side of the central barrier 18. They are movable across the air space between the switch blades 21 and 16 (or 22 and 17)as the latter are separated. Their ends enter notches 39 in the central barrier 18 so that they form insulating barriers to cut off any are between the open switch blades. Springs 40 force them forward.

When the switches are closed the barriers are held back by the upward ears 41 which bear against projections 42 on the upper part of the. carrier 19. The projections 42 have tapered lower edges 43 which as the carrier rises permit the barriers 37 to spring inward, and when the carrier is drawn down force the movable barriers 37 back.

A suitable type of fuse 27 is illustrated in Fig. 5. The conductors 26 are clamped on the opposite ends of a fuse strip 44 having a blowing point 45 of reduced cross-section in the small space between two plugs or pistons 46 which are tightly fitted onto the fuse strip and are carried loosely in a cylinder 47 mounted in the carrier. the cylinder being lined with insulating refractory material 48.

When the fuse blows the gas generated expels the plungers 46 forcibly and quickly out of the shell and separates-the burnt ends of the fuse strip so far as to prevent the maintenance of an arc between them. There is also a repulsive effect between the two conductors on opposite sides of the insulating carrier 19. The side walls 14 (Fig. 1) of the casing limit the distance to which the pistons can be blown. The conductors are detachably connected at their lower ends to the connectors 25 to facilitate replacement. 7

The casing is covered on the top by fixed lates 49, the space between which is spanned y flanges 50 on the carriers when the latter are down. This space is sufficient to permit the upward passage of the carrier and the fuses and connected conductor ends when the carrier is lifted. On the outer edges of the plates 49 there are hinged plates 51 which complete the closure when they are down. .When a fuse blows, the gases at opposite sides of the carrier will lift the hinged plates 51 and be blown in opposite directions to the right and left so as to avoid the forming of a conductive connection, such gas being largely metallic vapor which is highly conductive.

The separate carriers project above the easing so that they can be seized or clamped and lifted out separately for repairs or replacements.

' Figs. 6, 7 and 8 illustrate an advantageous design of the switch blades and movable barriers. The movable blade 21 has its lower end 52 of reduced width. The barrier 37 has a notch 53 in its end adapted to straddle the reduced end of the blade 21. When the blade is lifted from the position of Fig. 6 to that of Fig. 7, and while there is still a conducting path between the blades, the barrier 37 can advance to the point of engagement with the vertical barrier 18. Then as the upward movement of the switch blade is completed the barrier 37 will be thrown quickly across the remaining distance, closing the narrow path through which the current might otherwise jump.

Figs. 9 and 10 illustrate another design working on a similar principle. The upper blades 21 have reduced triangular end portions 54 entering the lower blades 55; the

plane of these blades extending in the-dircction of movement of slides 37. The latter have lugs 56 with inclined forward faces engaging the inclined faces of projections 57 mounted on the vertically moving carrier.

As the carrier is raised, the springs 40 press the slides 37 forward. The area of contact between the switch blades is diminished gradually. But there is some contact until the slides 37 are advanced nearly to their closing position. The final lifting movement of the switch blades permits the slides 37 to move entirely across the gaps to the position of Fig. 10.

d by ngeg mwvwifih the 60 of "rev-erg m'oimted entfixedqeivots' '61 and arms' "62 hearing undenprojections 63 on the 37g-fare' i eleas'e d tdbeqrf against the loflatleslfll .a-ndto spring across the as soon as the Blades are snific'iently elevated: To lower the "pari'ier and bladesythesl ides 37 are firstwiththfawnfby pressing *cl ownthe lever zums62.

1 Ti'gfim shows cdnstrtict'inn siinila rtb that of Fig, "9 iexcept thattthe slides 37 ate "urged is used: also th illu'sti'ztt'e 'a arising: with cover sectiensflfi hinged at the back insteadfof on their inner edges as in Figil. The lifting f "thectrversfifi' permitslthe L i-riers with H1911 blade 21 is lifted elem- (Fig.

' 'NOW' rangements ine-es The--Iuse's which Cles Q-f the insulating carrier, the separation liemg great j ing mechanismseethety eanumteaenmi illlCihQl d up the carrier 19. This mechanism Tiers will iilsofiilose the' spaces td prevent eurv 1 Deeded by riishfg fthe 1.

()l'iheil se this weungemem ijsi similarto 'l igliky 3 eeeiieieemm h the any; enemies--19 manuzil'lybr entomafi llya have emmeeted main switch will throw the entire load through the auxiliary switch which remains closed and the auxiliary fuse 31 will blow and thus completely break the circuit. When this happens the movable barriers of the main switch serve an important purpose in preventing current arcing across the terminals of the main switch. The fixed longitudinal barrier 15 will prevent the passage of any flaming gas from one to the other of the compartments carrying the main and auxiliary switches respectively.

-The scheme of breaking the circuit in this way by a: comparatively small fuse which blows upon the opening of the switch is claimed in a pending application of Thomas E. Murray, Jr. No. 257,861, filed February 29, 1928.

In case of a dead short circuit or similar sudden overload, greater than the automatic operating mechanism can take care of (or where no such automatic mechanism is'pro- Added) the fuses in the main switch will blow;

the comparative resistances in the branches of the circuit being regulated so that the -percentage of overload will be greatest I through the main switch. When this happens the entire load will be thrown on the auxiliary circuit and its fuse will blow immediately and completethe break in the circuit.

When either the auxiliary fuse alone or both sets of fuses have been blown, new fuses must be inserted before restoring the circuit. ,For this purpose the fuse carriers are lifted to bring the fuses above the cover of the box fuse, if only one be used) is preferably such that it will blow only upon the passage of a current which is substantially higher than its rated capacity; the rated capacity being the normal current on the circuit. The fuse should operate only with the current at least ten per cent above its rated capacity and preferably many times its normal (say fifteen times). This is to insure that it will not operate except onan extreme short circuit. I For anything less, the automatic mechanism will be depended upon to lift the carrier and open the switch.

On a two hundred ampere load, for ex 7 ample, a three thousand ampere fusemay be used. In this way I avoid any substantial heating of the fuse and any break from small troubles.

The ordinary fuses in electric circuits are designed for a very small overload, about five per cent in most cases. So that a two hundred ampere fuse is designed to blow at about two hundred and ten amperes. The

fuse in the auxiliary switch on the other hand is of very small capacity compared with the normal current so that it will blow immediately upon the opening of the main switch.

It may, for example, be a fuse of five or ten amperes capacity for a circuit carrying a normal load of two hundred amperes. And although the auxiliary fuse has its conductors 30 discomxectiblc at their lower ends from the circuit, yet this is not a switch in the ordinary sense. The detachable connectors are not used to open the circuit. It is only after the circuit is broken and the fuse is blown that the terminals are disconnected while the fuse is being replaced.

The movable barriers described are covered separately in another application and are claimed herein only in connection with the fuse arrangement.

Various modifications in detail may be made by those skilled in the art without departing from the invention as defined in the following claims.

I claim:

1.. Apparatus of the type described which comprises. a pair of electric circuit terminals, a movable barrier separating said terminals, a switch member-extending through said barrier and connecting said terminals and a fuse connected in parallel with said switch and of'a capacity to blow upon the opening of said switch.

2. The apparatus of claim 1, in which the fuse is mounted on a sliding barrier between said terminals.

3. The apparatus of claim 1 in which fuses are included in the switch of a capacity much greater than that of the fuse connected in parallel.

4. The apparatus of claim 1 in which an insulating plate is automatically moved between said terminals and said switch upon the opening of said switch.

5. Apparatus of the type described which comprises a pair of switch terminals for a high tension electric circuit, an enclosure for said terminals having an insulating barrier between said terminals, a slidable switch bridging said terminals across said barrier, an arc intercepting plate and means for automatically moving said plate into arc intercepting position against said barrier upon the sliding of said switch to open position.

(5. The apparatus of claim 5 and a fuse in said switch. I

7. The apparatus of claim 5 and a fuse connected in parallel between said terminals and of less capacity than said switch.

8. The apparatus of claim 5 and, a fuse connected in parallel between said terminals and of less capacity than said switch and a.

carrier for said fuse slidable in said barrier to sever the connection of said fuse to said terminals. a V

9. The apparatus of claim 5, a fuse connected in parallel between said terminals and of less capacity than said switch, a carrier for said fuse slidable in said barrier to sever the connection of said fuse to said terminals and an actuating means for said switch and fuse carrier tosuccessively'open said switch and shift said fuse carrier.

10. Apparatus of the type described which I 'comprises a pair of circuit terminals, a

switch bridging said terminals, a fuse bridging said terminals, means for separatlng said switch from said termlnals while said fuse is connected to said terminals andthen separating said fuse from said terminals.

11. Apparatus of the type described which comprises an enclosure having a barrier of insulating material, a pair of high tension electric terminals the terminals of said pair being on opposite sides of said barrier, a pair of carriers slidably mounted in said barrier, and projecting from opposite walls of said enclosure, a switch mounted on one of minals', and a fuse connected in parallel with said switch and of a capacity to blow upon the opening of said switch.

In witness whereof, I have hereunto signed my name.

THOMAS E. MURRAY.

said carriers to engage and bridge said ter- 7 minals, a fuse comprised in said switch, a second switch mounted on said second carrier and bridging said termlnals in parallel with said first switch, a fuse of less capacity than that of said first switch comprised in said second switch and an actuating means to successively engage said first and said second switch carriers and move them to open position. a

12. The apparatus of claim 11 and an arc quenching means slidable to en agement with said barrier between said terminals and the engaging ends of said switches.

13. The apparatus of claim 11, an arc quenching means slidable to engagement with said barrier between said terminals and the engaging ends of said switches, and in which the switches and quenching means are formed to limit the path and dimensions of the are as the quenching means moves to quenching position.

14. Apparatus of the type described which comprises an enclosure having an insulating barrier and a pair of electric terminals, the terminals of said pair being on opposite sides of said barrier, a carrier of insulating material slidable in said barrier and extending through opposite walls of said enclosure to form' separate compartments on opposite sides of said barrier, a switchvcarried by said carrier and bridging said terminal and breaking contact therewith upon the sliding of said carrier, and a fuse connecting said contacts in parallel with said switch and immediately after the opening of said switch, said fuse being of a less capacity than said switch. 7 Y 

